Tristan Matthews | 0461646 | 2013-11-14 16:09:34 -0500 | [diff] [blame] | 1 | .TH PCREGREP 1 |
| 2 | .SH NAME |
| 3 | pcregrep - a grep with Perl-compatible regular expressions. |
| 4 | .SH SYNOPSIS |
| 5 | .B pcregrep [options] [long options] [pattern] [path1 path2 ...] |
| 6 | . |
| 7 | .SH DESCRIPTION |
| 8 | .rs |
| 9 | .sp |
| 10 | \fBpcregrep\fP searches files for character patterns, in the same way as other |
| 11 | grep commands do, but it uses the PCRE regular expression library to support |
| 12 | patterns that are compatible with the regular expressions of Perl 5. See |
| 13 | .\" HREF |
| 14 | \fBpcrepattern\fP(3) |
| 15 | .\" |
| 16 | for a full description of syntax and semantics of the regular expressions |
| 17 | that PCRE supports. |
| 18 | .P |
| 19 | Patterns, whether supplied on the command line or in a separate file, are given |
| 20 | without delimiters. For example: |
| 21 | .sp |
| 22 | pcregrep Thursday /etc/motd |
| 23 | .sp |
| 24 | If you attempt to use delimiters (for example, by surrounding a pattern with |
| 25 | slashes, as is common in Perl scripts), they are interpreted as part of the |
| 26 | pattern. Quotes can of course be used to delimit patterns on the command line |
| 27 | because they are interpreted by the shell, and indeed they are required if a |
| 28 | pattern contains white space or shell metacharacters. |
| 29 | .P |
| 30 | The first argument that follows any option settings is treated as the single |
| 31 | pattern to be matched when neither \fB-e\fP nor \fB-f\fP is present. |
| 32 | Conversely, when one or both of these options are used to specify patterns, all |
| 33 | arguments are treated as path names. At least one of \fB-e\fP, \fB-f\fP, or an |
| 34 | argument pattern must be provided. |
| 35 | .P |
| 36 | If no files are specified, \fBpcregrep\fP reads the standard input. The |
| 37 | standard input can also be referenced by a name consisting of a single hyphen. |
| 38 | For example: |
| 39 | .sp |
| 40 | pcregrep some-pattern /file1 - /file3 |
| 41 | .sp |
| 42 | By default, each line that matches a pattern is copied to the standard |
| 43 | output, and if there is more than one file, the file name is output at the |
| 44 | start of each line, followed by a colon. However, there are options that can |
| 45 | change how \fBpcregrep\fP behaves. In particular, the \fB-M\fP option makes it |
| 46 | possible to search for patterns that span line boundaries. What defines a line |
| 47 | boundary is controlled by the \fB-N\fP (\fB--newline\fP) option. |
| 48 | .P |
| 49 | The amount of memory used for buffering files that are being scanned is |
| 50 | controlled by a parameter that can be set by the \fB--buffer-size\fP option. |
| 51 | The default value for this parameter is specified when \fBpcregrep\fP is built, |
| 52 | with the default default being 20K. A block of memory three times this size is |
| 53 | used (to allow for buffering "before" and "after" lines). An error occurs if a |
| 54 | line overflows the buffer. |
| 55 | .P |
| 56 | Patterns are limited to 8K or BUFSIZ bytes, whichever is the greater. BUFSIZ is |
| 57 | defined in \fB<stdio.h>\fP. When there is more than one pattern (specified by |
| 58 | the use of \fB-e\fP and/or \fB-f\fP), each pattern is applied to each line in |
| 59 | the order in which they are defined, except that all the \fB-e\fP patterns are |
| 60 | tried before the \fB-f\fP patterns. |
| 61 | .P |
| 62 | By default, as soon as one pattern matches (or fails to match when \fB-v\fP is |
| 63 | used), no further patterns are considered. However, if \fB--colour\fP (or |
| 64 | \fB--color\fP) is used to colour the matching substrings, or if |
| 65 | \fB--only-matching\fP, \fB--file-offsets\fP, or \fB--line-offsets\fP is used to |
| 66 | output only the part of the line that matched (either shown literally, or as an |
| 67 | offset), scanning resumes immediately following the match, so that further |
| 68 | matches on the same line can be found. If there are multiple patterns, they are |
| 69 | all tried on the remainder of the line, but patterns that follow the one that |
| 70 | matched are not tried on the earlier part of the line. |
| 71 | .P |
| 72 | This is the same behaviour as GNU grep, but it does mean that the order in |
| 73 | which multiple patterns are specified can affect the output when one of the |
| 74 | above options is used. |
| 75 | .P |
| 76 | Patterns that can match an empty string are accepted, but empty string |
| 77 | matches are never recognized. An example is the pattern "(super)?(man)?", in |
| 78 | which all components are optional. This pattern finds all occurrences of both |
| 79 | "super" and "man"; the output differs from matching with "super|man" when only |
| 80 | the matching substrings are being shown. |
| 81 | .P |
| 82 | If the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variable is set, |
| 83 | \fBpcregrep\fP uses the value to set a locale when calling the PCRE library. |
| 84 | The \fB--locale\fP option can be used to override this. |
| 85 | . |
| 86 | . |
| 87 | .SH "SUPPORT FOR COMPRESSED FILES" |
| 88 | .rs |
| 89 | .sp |
| 90 | It is possible to compile \fBpcregrep\fP so that it uses \fBlibz\fP or |
| 91 | \fBlibbz2\fP to read files whose names end in \fB.gz\fP or \fB.bz2\fP, |
| 92 | respectively. You can find out whether your binary has support for one or both |
| 93 | of these file types by running it with the \fB--help\fP option. If the |
| 94 | appropriate support is not present, files are treated as plain text. The |
| 95 | standard input is always so treated. |
| 96 | . |
| 97 | . |
| 98 | .SH OPTIONS |
| 99 | .rs |
| 100 | .sp |
| 101 | The order in which some of the options appear can affect the output. For |
| 102 | example, both the \fB-h\fP and \fB-l\fP options affect the printing of file |
| 103 | names. Whichever comes later in the command line will be the one that takes |
| 104 | effect. Numerical values for options may be followed by K or M, to signify |
| 105 | multiplication by 1024 or 1024*1024 respectively. |
| 106 | .TP 10 |
| 107 | \fB--\fP |
| 108 | This terminates the list of options. It is useful if the next item on the |
| 109 | command line starts with a hyphen but is not an option. This allows for the |
| 110 | processing of patterns and filenames that start with hyphens. |
| 111 | .TP |
| 112 | \fB-A\fP \fInumber\fP, \fB--after-context=\fP\fInumber\fP |
| 113 | Output \fInumber\fP lines of context after each matching line. If filenames |
| 114 | and/or line numbers are being output, a hyphen separator is used instead of a |
| 115 | colon for the context lines. A line containing "--" is output between each |
| 116 | group of lines, unless they are in fact contiguous in the input file. The value |
| 117 | of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP |
| 118 | guarantees to have up to 8K of following text available for context output. |
| 119 | .TP |
| 120 | \fB-B\fP \fInumber\fP, \fB--before-context=\fP\fInumber\fP |
| 121 | Output \fInumber\fP lines of context before each matching line. If filenames |
| 122 | and/or line numbers are being output, a hyphen separator is used instead of a |
| 123 | colon for the context lines. A line containing "--" is output between each |
| 124 | group of lines, unless they are in fact contiguous in the input file. The value |
| 125 | of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP |
| 126 | guarantees to have up to 8K of preceding text available for context output. |
| 127 | .TP |
| 128 | \fB--buffer-size=\fP\fInumber\fP |
| 129 | Set the parameter that controls how much memory is used for buffering files |
| 130 | that are being scanned. |
| 131 | .TP |
| 132 | \fB-C\fP \fInumber\fP, \fB--context=\fP\fInumber\fP |
| 133 | Output \fInumber\fP lines of context both before and after each matching line. |
| 134 | This is equivalent to setting both \fB-A\fP and \fB-B\fP to the same value. |
| 135 | .TP |
| 136 | \fB-c\fP, \fB--count\fP |
| 137 | Do not output individual lines from the files that are being scanned; instead |
| 138 | output the number of lines that would otherwise have been shown. If no lines |
| 139 | are selected, the number zero is output. If several files are are being |
| 140 | scanned, a count is output for each of them. However, if the |
| 141 | \fB--files-with-matches\fP option is also used, only those files whose counts |
| 142 | are greater than zero are listed. When \fB-c\fP is used, the \fB-A\fP, |
| 143 | \fB-B\fP, and \fB-C\fP options are ignored. |
| 144 | .TP |
| 145 | \fB--colour\fP, \fB--color\fP |
| 146 | If this option is given without any data, it is equivalent to "--colour=auto". |
| 147 | If data is required, it must be given in the same shell item, separated by an |
| 148 | equals sign. |
| 149 | .TP |
| 150 | \fB--colour=\fP\fIvalue\fP, \fB--color=\fP\fIvalue\fP |
| 151 | This option specifies under what circumstances the parts of a line that matched |
| 152 | a pattern should be coloured in the output. By default, the output is not |
| 153 | coloured. The value (which is optional, see above) may be "never", "always", or |
| 154 | "auto". In the latter case, colouring happens only if the standard output is |
| 155 | connected to a terminal. More resources are used when colouring is enabled, |
| 156 | because \fBpcregrep\fP has to search for all possible matches in a line, not |
| 157 | just one, in order to colour them all. |
| 158 | .sp |
| 159 | The colour that is used can be specified by setting the environment variable |
| 160 | PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a |
| 161 | string of two numbers, separated by a semicolon. They are copied directly into |
| 162 | the control string for setting colour on a terminal, so it is your |
| 163 | responsibility to ensure that they make sense. If neither of the environment |
| 164 | variables is set, the default is "1;31", which gives red. |
| 165 | .TP |
| 166 | \fB-D\fP \fIaction\fP, \fB--devices=\fP\fIaction\fP |
| 167 | If an input path is not a regular file or a directory, "action" specifies how |
| 168 | it is to be processed. Valid values are "read" (the default) or "skip" |
| 169 | (silently skip the path). |
| 170 | .TP |
| 171 | \fB-d\fP \fIaction\fP, \fB--directories=\fP\fIaction\fP |
| 172 | If an input path is a directory, "action" specifies how it is to be processed. |
| 173 | Valid values are "read" (the default), "recurse" (equivalent to the \fB-r\fP |
| 174 | option), or "skip" (silently skip the path). In the default case, directories |
| 175 | are read as if they were ordinary files. In some operating systems the effect |
| 176 | of reading a directory like this is an immediate end-of-file. |
| 177 | .TP |
| 178 | \fB-e\fP \fIpattern\fP, \fB--regex=\fP\fIpattern\fP, \fB--regexp=\fP\fIpattern\fP |
| 179 | Specify a pattern to be matched. This option can be used multiple times in |
| 180 | order to specify several patterns. It can also be used as a way of specifying a |
| 181 | single pattern that starts with a hyphen. When \fB-e\fP is used, no argument |
| 182 | pattern is taken from the command line; all arguments are treated as file |
| 183 | names. There is an overall maximum of 100 patterns. They are applied to each |
| 184 | line in the order in which they are defined until one matches (or fails to |
| 185 | match if \fB-v\fP is used). If \fB-f\fP is used with \fB-e\fP, the command line |
| 186 | patterns are matched first, followed by the patterns from the file, independent |
| 187 | of the order in which these options are specified. Note that multiple use of |
| 188 | \fB-e\fP is not the same as a single pattern with alternatives. For example, |
| 189 | X|Y finds the first character in a line that is X or Y, whereas if the two |
| 190 | patterns are given separately, \fBpcregrep\fP finds X if it is present, even if |
| 191 | it follows Y in the line. It finds Y only if there is no X in the line. This |
| 192 | really matters only if you are using \fB-o\fP to show the part(s) of the line |
| 193 | that matched. |
| 194 | .TP |
| 195 | \fB--exclude\fP=\fIpattern\fP |
| 196 | When \fBpcregrep\fP is searching the files in a directory as a consequence of |
| 197 | the \fB-r\fP (recursive search) option, any regular files whose names match the |
| 198 | pattern are excluded. Subdirectories are not excluded by this option; they are |
| 199 | searched recursively, subject to the \fB--exclude-dir\fP and |
| 200 | \fB--include_dir\fP options. The pattern is a PCRE regular expression, and is |
| 201 | matched against the final component of the file name (not the entire path). If |
| 202 | a file name matches both \fB--include\fP and \fB--exclude\fP, it is excluded. |
| 203 | There is no short form for this option. |
| 204 | .TP |
| 205 | \fB--exclude-dir\fP=\fIpattern\fP |
| 206 | When \fBpcregrep\fP is searching the contents of a directory as a consequence |
| 207 | of the \fB-r\fP (recursive search) option, any subdirectories whose names match |
| 208 | the pattern are excluded. (Note that the \fP--exclude\fP option does not affect |
| 209 | subdirectories.) The pattern is a PCRE regular expression, and is matched |
| 210 | against the final component of the name (not the entire path). If a |
| 211 | subdirectory name matches both \fB--include-dir\fP and \fB--exclude-dir\fP, it |
| 212 | is excluded. There is no short form for this option. |
| 213 | .TP |
| 214 | \fB-F\fP, \fB--fixed-strings\fP |
| 215 | Interpret each pattern as a list of fixed strings, separated by newlines, |
| 216 | instead of as a regular expression. The \fB-w\fP (match as a word) and \fB-x\fP |
| 217 | (match whole line) options can be used with \fB-F\fP. They apply to each of the |
| 218 | fixed strings. A line is selected if any of the fixed strings are found in it |
| 219 | (subject to \fB-w\fP or \fB-x\fP, if present). |
| 220 | .TP |
| 221 | \fB-f\fP \fIfilename\fP, \fB--file=\fP\fIfilename\fP |
| 222 | Read a number of patterns from the file, one per line, and match them against |
| 223 | each line of input. A data line is output if any of the patterns match it. The |
| 224 | filename can be given as "-" to refer to the standard input. When \fB-f\fP is |
| 225 | used, patterns specified on the command line using \fB-e\fP may also be |
| 226 | present; they are tested before the file's patterns. However, no other pattern |
| 227 | is taken from the command line; all arguments are treated as file names. There |
| 228 | is an overall maximum of 100 patterns. Trailing white space is removed from |
| 229 | each line, and blank lines are ignored. An empty file contains no patterns and |
| 230 | therefore matches nothing. See also the comments about multiple patterns versus |
| 231 | a single pattern with alternatives in the description of \fB-e\fP above. |
| 232 | .TP |
| 233 | \fB--file-offsets\fP |
| 234 | Instead of showing lines or parts of lines that match, show each match as an |
| 235 | offset from the start of the file and a length, separated by a comma. In this |
| 236 | mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP |
| 237 | options are ignored. If there is more than one match in a line, each of them is |
| 238 | shown separately. This option is mutually exclusive with \fB--line-offsets\fP |
| 239 | and \fB--only-matching\fP. |
| 240 | .TP |
| 241 | \fB-H\fP, \fB--with-filename\fP |
| 242 | Force the inclusion of the filename at the start of output lines when searching |
| 243 | a single file. By default, the filename is not shown in this case. For matching |
| 244 | lines, the filename is followed by a colon; for context lines, a hyphen |
| 245 | separator is used. If a line number is also being output, it follows the file |
| 246 | name. |
| 247 | .TP |
| 248 | \fB-h\fP, \fB--no-filename\fP |
| 249 | Suppress the output filenames when searching multiple files. By default, |
| 250 | filenames are shown when multiple files are searched. For matching lines, the |
| 251 | filename is followed by a colon; for context lines, a hyphen separator is used. |
| 252 | If a line number is also being output, it follows the file name. |
| 253 | .TP |
| 254 | \fB--help\fP |
| 255 | Output a help message, giving brief details of the command options and file |
| 256 | type support, and then exit. |
| 257 | .TP |
| 258 | \fB-i\fP, \fB--ignore-case\fP |
| 259 | Ignore upper/lower case distinctions during comparisons. |
| 260 | .TP |
| 261 | \fB--include\fP=\fIpattern\fP |
| 262 | When \fBpcregrep\fP is searching the files in a directory as a consequence of |
| 263 | the \fB-r\fP (recursive search) option, only those regular files whose names |
| 264 | match the pattern are included. Subdirectories are always included and searched |
| 265 | recursively, subject to the \fP--include-dir\fP and \fB--exclude-dir\fP |
| 266 | options. The pattern is a PCRE regular expression, and is matched against the |
| 267 | final component of the file name (not the entire path). If a file name matches |
| 268 | both \fB--include\fP and \fB--exclude\fP, it is excluded. There is no short |
| 269 | form for this option. |
| 270 | .TP |
| 271 | \fB--include-dir\fP=\fIpattern\fP |
| 272 | When \fBpcregrep\fP is searching the contents of a directory as a consequence |
| 273 | of the \fB-r\fP (recursive search) option, only those subdirectories whose |
| 274 | names match the pattern are included. (Note that the \fB--include\fP option |
| 275 | does not affect subdirectories.) The pattern is a PCRE regular expression, and |
| 276 | is matched against the final component of the name (not the entire path). If a |
| 277 | subdirectory name matches both \fB--include-dir\fP and \fB--exclude-dir\fP, it |
| 278 | is excluded. There is no short form for this option. |
| 279 | .TP |
| 280 | \fB-L\fP, \fB--files-without-match\fP |
| 281 | Instead of outputting lines from the files, just output the names of the files |
| 282 | that do not contain any lines that would have been output. Each file name is |
| 283 | output once, on a separate line. |
| 284 | .TP |
| 285 | \fB-l\fP, \fB--files-with-matches\fP |
| 286 | Instead of outputting lines from the files, just output the names of the files |
| 287 | containing lines that would have been output. Each file name is output |
| 288 | once, on a separate line. Searching normally stops as soon as a matching line |
| 289 | is found in a file. However, if the \fB-c\fP (count) option is also used, |
| 290 | matching continues in order to obtain the correct count, and those files that |
| 291 | have at least one match are listed along with their counts. Using this option |
| 292 | with \fB-c\fP is a way of suppressing the listing of files with no matches. |
| 293 | .TP |
| 294 | \fB--label\fP=\fIname\fP |
| 295 | This option supplies a name to be used for the standard input when file names |
| 296 | are being output. If not supplied, "(standard input)" is used. There is no |
| 297 | short form for this option. |
| 298 | .TP |
| 299 | \fB--line-buffered\fP |
| 300 | When this option is given, input is read and processed line by line, and the |
| 301 | output is flushed after each write. By default, input is read in large chunks, |
| 302 | unless \fBpcregrep\fP can determine that it is reading from a terminal (which |
| 303 | is currently possible only in Unix environments). Output to terminal is |
| 304 | normally automatically flushed by the operating system. This option can be |
| 305 | useful when the input or output is attached to a pipe and you do not want |
| 306 | \fBpcregrep\fP to buffer up large amounts of data. However, its use will affect |
| 307 | performance, and the \fB-M\fP (multiline) option ceases to work. |
| 308 | .TP |
| 309 | \fB--line-offsets\fP |
| 310 | Instead of showing lines or parts of lines that match, show each match as a |
| 311 | line number, the offset from the start of the line, and a length. The line |
| 312 | number is terminated by a colon (as usual; see the \fB-n\fP option), and the |
| 313 | offset and length are separated by a comma. In this mode, no context is shown. |
| 314 | That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are ignored. If there is |
| 315 | more than one match in a line, each of them is shown separately. This option is |
| 316 | mutually exclusive with \fB--file-offsets\fP and \fB--only-matching\fP. |
| 317 | .TP |
| 318 | \fB--locale\fP=\fIlocale-name\fP |
| 319 | This option specifies a locale to be used for pattern matching. It overrides |
| 320 | the value in the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variables. If no |
| 321 | locale is specified, the PCRE library's default (usually the "C" locale) is |
| 322 | used. There is no short form for this option. |
| 323 | .TP |
| 324 | \fB--match-limit\fP=\fInumber\fP |
| 325 | Processing some regular expression patterns can require a very large amount of |
| 326 | memory, leading in some cases to a program crash if not enough is available. |
| 327 | Other patterns may take a very long time to search for all possible matching |
| 328 | strings. The \fBpcre_exec()\fP function that is called by \fBpcregrep\fP to do |
| 329 | the matching has two parameters that can limit the resources that it uses. |
| 330 | .sp |
| 331 | The \fB--match-limit\fP option provides a means of limiting resource usage |
| 332 | when processing patterns that are not going to match, but which have a very |
| 333 | large number of possibilities in their search trees. The classic example is a |
| 334 | pattern that uses nested unlimited repeats. Internally, PCRE uses a function |
| 335 | called \fBmatch()\fP which it calls repeatedly (sometimes recursively). The |
| 336 | limit set by \fB--match-limit\fP is imposed on the number of times this |
| 337 | function is called during a match, which has the effect of limiting the amount |
| 338 | of backtracking that can take place. |
| 339 | .sp |
| 340 | The \fB--recursion-limit\fP option is similar to \fB--match-limit\fP, but |
| 341 | instead of limiting the total number of times that \fBmatch()\fP is called, it |
| 342 | limits the depth of recursive calls, which in turn limits the amount of memory |
| 343 | that can be used. The recursion depth is a smaller number than the total number |
| 344 | of calls, because not all calls to \fBmatch()\fP are recursive. This limit is |
| 345 | of use only if it is set smaller than \fB--match-limit\fP. |
| 346 | .sp |
| 347 | There are no short forms for these options. The default settings are specified |
| 348 | when the PCRE library is compiled, with the default default being 10 million. |
| 349 | .TP |
| 350 | \fB-M\fP, \fB--multiline\fP |
| 351 | Allow patterns to match more than one line. When this option is given, patterns |
| 352 | may usefully contain literal newline characters and internal occurrences of ^ |
| 353 | and $ characters. The output for a successful match may consist of more than |
| 354 | one line, the last of which is the one in which the match ended. If the matched |
| 355 | string ends with a newline sequence the output ends at the end of that line. |
| 356 | .sp |
| 357 | When this option is set, the PCRE library is called in "multiline" mode. |
| 358 | There is a limit to the number of lines that can be matched, imposed by the way |
| 359 | that \fBpcregrep\fP buffers the input file as it scans it. However, |
| 360 | \fBpcregrep\fP ensures that at least 8K characters or the rest of the document |
| 361 | (whichever is the shorter) are available for forward matching, and similarly |
| 362 | the previous 8K characters (or all the previous characters, if fewer than 8K) |
| 363 | are guaranteed to be available for lookbehind assertions. This option does not |
| 364 | work when input is read line by line (see \fP--line-buffered\fP.) |
| 365 | .TP |
| 366 | \fB-N\fP \fInewline-type\fP, \fB--newline\fP=\fInewline-type\fP |
| 367 | The PCRE library supports five different conventions for indicating |
| 368 | the ends of lines. They are the single-character sequences CR (carriage return) |
| 369 | and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention, |
| 370 | which recognizes any of the preceding three types, and an "any" convention, in |
| 371 | which any Unicode line ending sequence is assumed to end a line. The Unicode |
| 372 | sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF |
| 373 | (form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and |
| 374 | PS (paragraph separator, U+2029). |
| 375 | .sp |
| 376 | When the PCRE library is built, a default line-ending sequence is specified. |
| 377 | This is normally the standard sequence for the operating system. Unless |
| 378 | otherwise specified by this option, \fBpcregrep\fP uses the library's default. |
| 379 | The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This |
| 380 | makes it possible to use \fBpcregrep\fP on files that have come from other |
| 381 | environments without having to modify their line endings. If the data that is |
| 382 | being scanned does not agree with the convention set by this option, |
| 383 | \fBpcregrep\fP may behave in strange ways. |
| 384 | .TP |
| 385 | \fB-n\fP, \fB--line-number\fP |
| 386 | Precede each output line by its line number in the file, followed by a colon |
| 387 | for matching lines or a hyphen for context lines. If the filename is also being |
| 388 | output, it precedes the line number. This option is forced if |
| 389 | \fB--line-offsets\fP is used. |
| 390 | .TP |
| 391 | \fB--no-jit\fP |
| 392 | If the PCRE library is built with support for just-in-time compiling (which |
| 393 | speeds up matching), \fBpcregrep\fP automatically makes use of this, unless it |
| 394 | was explicitly disabled at build time. This option can be used to disable the |
| 395 | use of JIT at run time. It is provided for testing and working round problems. |
| 396 | It should never be needed in normal use. |
| 397 | .TP |
| 398 | \fB-o\fP, \fB--only-matching\fP |
| 399 | Show only the part of the line that matched a pattern instead of the whole |
| 400 | line. In this mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and |
| 401 | \fB-C\fP options are ignored. If there is more than one match in a line, each |
| 402 | of them is shown separately. If \fB-o\fP is combined with \fB-v\fP (invert the |
| 403 | sense of the match to find non-matching lines), no output is generated, but the |
| 404 | return code is set appropriately. If the matched portion of the line is empty, |
| 405 | nothing is output unless the file name or line number are being printed, in |
| 406 | which case they are shown on an otherwise empty line. This option is mutually |
| 407 | exclusive with \fB--file-offsets\fP and \fB--line-offsets\fP. |
| 408 | .TP |
| 409 | \fB-o\fP\fInumber\fP, \fB--only-matching\fP=\fInumber\fP |
| 410 | Show only the part of the line that matched the capturing parentheses of the |
| 411 | given number. Up to 32 capturing parentheses are supported. Because these |
| 412 | options can be given without an argument (see above), if an argument is |
| 413 | present, it must be given in the same shell item, for example, -o3 or |
| 414 | --only-matching=2. The comments given for the non-argument case above also |
| 415 | apply to this case. If the specified capturing parentheses do not exist in the |
| 416 | pattern, or were not set in the match, nothing is output unless the file name |
| 417 | or line number are being printed. |
| 418 | .TP |
| 419 | \fB-q\fP, \fB--quiet\fP |
| 420 | Work quietly, that is, display nothing except error messages. The exit |
| 421 | status indicates whether or not any matches were found. |
| 422 | .TP |
| 423 | \fB-r\fP, \fB--recursive\fP |
| 424 | If any given path is a directory, recursively scan the files it contains, |
| 425 | taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a |
| 426 | directory is read as a normal file; in some operating systems this gives an |
| 427 | immediate end-of-file. This option is a shorthand for setting the \fB-d\fP |
| 428 | option to "recurse". |
| 429 | .TP |
| 430 | \fB--recursion-limit\fP=\fInumber\fP |
| 431 | See \fB--match-limit\fP above. |
| 432 | .TP |
| 433 | \fB-s\fP, \fB--no-messages\fP |
| 434 | Suppress error messages about non-existent or unreadable files. Such files are |
| 435 | quietly skipped. However, the return code is still 2, even if matches were |
| 436 | found in other files. |
| 437 | .TP |
| 438 | \fB-u\fP, \fB--utf-8\fP |
| 439 | Operate in UTF-8 mode. This option is available only if PCRE has been compiled |
| 440 | with UTF-8 support. Both patterns and subject lines must be valid strings of |
| 441 | UTF-8 characters. |
| 442 | .TP |
| 443 | \fB-V\fP, \fB--version\fP |
| 444 | Write the version numbers of \fBpcregrep\fP and the PCRE library that is being |
| 445 | used to the standard error stream. |
| 446 | .TP |
| 447 | \fB-v\fP, \fB--invert-match\fP |
| 448 | Invert the sense of the match, so that lines which do \fInot\fP match any of |
| 449 | the patterns are the ones that are found. |
| 450 | .TP |
| 451 | \fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP |
| 452 | Force the patterns to match only whole words. This is equivalent to having \eb |
| 453 | at the start and end of the pattern. |
| 454 | .TP |
| 455 | \fB-x\fP, \fB--line-regex\fP, \fB--line-regexp\fP |
| 456 | Force the patterns to be anchored (each must start matching at the beginning of |
| 457 | a line) and in addition, require them to match entire lines. This is |
| 458 | equivalent to having ^ and $ characters at the start and end of each |
| 459 | alternative branch in every pattern. |
| 460 | . |
| 461 | . |
| 462 | .SH "ENVIRONMENT VARIABLES" |
| 463 | .rs |
| 464 | .sp |
| 465 | The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that |
| 466 | order, for a locale. The first one that is set is used. This can be overridden |
| 467 | by the \fB--locale\fP option. If no locale is set, the PCRE library's default |
| 468 | (usually the "C" locale) is used. |
| 469 | . |
| 470 | . |
| 471 | .SH "NEWLINES" |
| 472 | .rs |
| 473 | .sp |
| 474 | The \fB-N\fP (\fB--newline\fP) option allows \fBpcregrep\fP to scan files with |
| 475 | different newline conventions from the default. However, the setting of this |
| 476 | option does not affect the way in which \fBpcregrep\fP writes information to |
| 477 | the standard error and output streams. It uses the string "\en" in C |
| 478 | \fBprintf()\fP calls to indicate newlines, relying on the C I/O library to |
| 479 | convert this to an appropriate sequence if the output is sent to a file. |
| 480 | . |
| 481 | . |
| 482 | .SH "OPTIONS COMPATIBILITY" |
| 483 | .rs |
| 484 | .sp |
| 485 | Many of the short and long forms of \fBpcregrep\fP's options are the same |
| 486 | as in the GNU \fBgrep\fP program (version 2.5.4). Any long option of the form |
| 487 | \fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP |
| 488 | (PCRE terminology). However, the \fB--file-offsets\fP, \fB--include-dir\fP, |
| 489 | \fB--line-offsets\fP, \fB--locale\fP, \fB--match-limit\fP, \fB-M\fP, |
| 490 | \fB--multiline\fP, \fB-N\fP, \fB--newline\fP, \fB--recursion-limit\fP, |
| 491 | \fB-u\fP, and \fB--utf-8\fP options are specific to \fBpcregrep\fP, as is the |
| 492 | use of the \fB--only-matching\fP option with a capturing parentheses number. |
| 493 | .P |
| 494 | Although most of the common options work the same way, a few are different in |
| 495 | \fBpcregrep\fP. For example, the \fB--include\fP option's argument is a glob |
| 496 | for GNU \fBgrep\fP, but a regular expression for \fBpcregrep\fP. If both the |
| 497 | \fB-c\fP and \fB-l\fP options are given, GNU grep lists only file names, |
| 498 | without counts, but \fBpcregrep\fP gives the counts. |
| 499 | . |
| 500 | . |
| 501 | .SH "OPTIONS WITH DATA" |
| 502 | .rs |
| 503 | .sp |
| 504 | There are four different ways in which an option with data can be specified. |
| 505 | If a short form option is used, the data may follow immediately, or (with one |
| 506 | exception) in the next command line item. For example: |
| 507 | .sp |
| 508 | -f/some/file |
| 509 | -f /some/file |
| 510 | .sp |
| 511 | The exception is the \fB-o\fP option, which may appear with or without data. |
| 512 | Because of this, if data is present, it must follow immediately in the same |
| 513 | item, for example -o3. |
| 514 | .P |
| 515 | If a long form option is used, the data may appear in the same command line |
| 516 | item, separated by an equals character, or (with two exceptions) it may appear |
| 517 | in the next command line item. For example: |
| 518 | .sp |
| 519 | --file=/some/file |
| 520 | --file /some/file |
| 521 | .sp |
| 522 | Note, however, that if you want to supply a file name beginning with ~ as data |
| 523 | in a shell command, and have the shell expand ~ to a home directory, you must |
| 524 | separate the file name from the option, because the shell does not treat ~ |
| 525 | specially unless it is at the start of an item. |
| 526 | .P |
| 527 | The exceptions to the above are the \fB--colour\fP (or \fB--color\fP) and |
| 528 | \fB--only-matching\fP options, for which the data is optional. If one of these |
| 529 | options does have data, it must be given in the first form, using an equals |
| 530 | character. Otherwise \fBpcregrep\fP will assume that it has no data. |
| 531 | . |
| 532 | . |
| 533 | .SH "MATCHING ERRORS" |
| 534 | .rs |
| 535 | .sp |
| 536 | It is possible to supply a regular expression that takes a very long time to |
| 537 | fail to match certain lines. Such patterns normally involve nested indefinite |
| 538 | repeats, for example: (a+)*\ed when matched against a line of a's with no final |
| 539 | digit. The PCRE matching function has a resource limit that causes it to abort |
| 540 | in these circumstances. If this happens, \fBpcregrep\fP outputs an error |
| 541 | message and the line that caused the problem to the standard error stream. If |
| 542 | there are more than 20 such errors, \fBpcregrep\fP gives up. |
| 543 | .P |
| 544 | The \fB--match-limit\fP option of \fBpcregrep\fP can be used to set the overall |
| 545 | resource limit; there is a second option called \fB--recursion-limit\fP that |
| 546 | sets a limit on the amount of memory (usually stack) that is used (see the |
| 547 | discussion of these options above). |
| 548 | . |
| 549 | . |
| 550 | .SH DIAGNOSTICS |
| 551 | .rs |
| 552 | .sp |
| 553 | Exit status is 0 if any matches were found, 1 if no matches were found, and 2 |
| 554 | for syntax errors, overlong lines, non-existent or inaccessible files (even if |
| 555 | matches were found in other files) or too many matching errors. Using the |
| 556 | \fB-s\fP option to suppress error messages about inaccessible files does not |
| 557 | affect the return code. |
| 558 | . |
| 559 | . |
| 560 | .SH "SEE ALSO" |
| 561 | .rs |
| 562 | .sp |
| 563 | \fBpcrepattern\fP(3), \fBpcretest\fP(1). |
| 564 | . |
| 565 | . |
| 566 | .SH AUTHOR |
| 567 | .rs |
| 568 | .sp |
| 569 | .nf |
| 570 | Philip Hazel |
| 571 | University Computing Service |
| 572 | Cambridge CB2 3QH, England. |
| 573 | .fi |
| 574 | . |
| 575 | . |
| 576 | .SH REVISION |
| 577 | .rs |
| 578 | .sp |
| 579 | .nf |
| 580 | Last updated: 06 September 2011 |
| 581 | Copyright (c) 1997-2011 University of Cambridge. |
| 582 | .fi |